Nitro amines and process for preparing same



Patented Aug. 24, 1948 UNITED STATES PATENT {OFFICE NI ERO 'WAMNES ANDPROCESS FOR .r-REPARINGSAME naromdaehns ng "rem-e 'Haiita-Iiid fas'signor to commercial-solvent corporati 'rerrenaute, Inil.,a corporation of Maryland NoDrawinle; 'A-pplication J anuaryS, 1945, =-Serial No.-571,954

My invention relates "to' manufacture of new and useful symmetrical =2-nitro-2 alk-yl-lilz-N diphenyl-l, 3-propan'e diamines. More specifically the process of this invention comprises causing a reaction in thefpr'e's'ene'eof a basic position in situ of'a; z-nitrmz-mkyi-R program-" diol, that is, to react the phenyl amine"with"'2- nitro-Z-alkyl-l, 3-propaned iol instead of with a mixture of formaldehyde and nitroalkane. -By means of this process the products of thisinvention can be produced, as disclosed in the following specific examples, these products oomprising symmetrical 2'-'ni'tro --2 alkyl' -23- propane diamines whose pheny 'ou' substituted with a substituent selected, frem lie group consisting of hail'ogen alkyl NGz'AQH and COzH.

This case is a continuation-impart of-my application Serial No. 473,523 filed J anuary 25, 1943, now abandoned.

As examples of compounds which oan-beproduced by myproc'ess, there maybe mentioned, Z-nitro-Z-methyl- N ,N- diphenyl -l,3-1prbpa'nediamine; 2-nitro-2-ethyl=N,N"-diphenyl panediamine; '2-nitro-2-methyl N;N bis' rophenyl) -l-,'3 propanediamine; 2"-' 'nitro=2-methyl N,N'- di-p-tolyl l=,3 propanediamine; 2- nitro-2-methyl-N,N'-bis(p-nitroplie 3 panediamine; Z-nitro 2 -="metl'iyl N',N-'-*--bis"=( 2- methyl -4- diethylaminophenyl) -1,3- propanediamine; 2-nitro'-2-metliyl -'N,N'-bis(4 dimethylaminophenyl) 1,3 propanediamine; 2-nitro-2- methyl-N,N'-di-p-'xeriyl -le3 propanediamine; 2- nitro-Z-methyl- N,N- bis 2,4 climethylphenylg l,3-propanediamine; 2nitro 2 methyl N,N- bis(2,4-dich1or0pheny1) 1,3 propanediamine;

also the following compounds-and their ikali metal derivatives: 2-'nitrd'-2--*1h-etliyl NN' blslphydroxyphenyl) -1,3-P, Opanediaminef mare-2- methyl-N,N"-bis (O-earboXyphenyli-I, propanebis-(manner- 2 boxyphenyl) 1,3 propanediainine; 2 nitro 2- iiiethyl Nfl' bis-w-siilfo :4 -'methy1phenyl') -1,3- propanedi'amine; 2-nit'r'o-2-inethyl N,N -'bis'(2- methyl- -hydroxypheny1) 1,3 propane'diamine and the like.

According to my invention, these nitro amines are prepared by adding formaldehyde to a mixture of an aromatic amine and a primary nitroparafiin having more than one carbon atom. This reaction is-carr'ied out in the presence of a 'basic "catalyst and incertain instances it will be found advantageous to effect the same with the aid of a solvent such as methanol, ethanol,

'butanol, pyridine, triethylamine, tributyl amine, and the like.

A modified and frequently-preferred procedure for 'pieparingthe compounds of "my invention,

involves" reacting "the aromatic amine with a primary 'nitroal'oohol-derived from the primary nitropa'rafiin and -forn'ialdehyde described above. This reaction is, likewise, carried out in the 'presenceef a basic catalyst. Underthese conditions, the primary nitroalcohol is believed to decompose int'o formaldehyde "and the primary nitropar'aifin from which it was derived, thus resulting in the same type of reaction mixture as that obtained when formaldehyde and nitroparaflin are used separately.

Since both of the above-described procedures fundamentally involve reaction mixtures containing formaldehyde, a primary nitropa'rafiin having-more than one carbon atom, and an aromatici'ainine, it..:may be seenthat the reactions oocurring thereifi, in all essential respects, can 'beconsidered"equivalents. -It is to-be specifically understood, therefore-, that the terminology employed in certain of the appended process'cl'aims =is to1-be' construed to cover both of the foreugoin'g modifications.

"Temperatures ma "be employed which range rrom.25=30.=c. to-reflux temperature of the reaction" mixture. However in general, I have fou'n'd it preferable to carry 'out the imajority pi sueir rfeacti'ons at a temperatur'eef about In the ease 6f ai mati'caniifie's having a fidh'dth'lfidf anaemic roup, such as-a Gar- :eoxyr gmup, it is preferable 'to c'o'nve'rtthem -lioi tlili crfspbfidffig amalr metal sans by treatment with a;'stoiehiometricalquantity of the de- "swee ener; niet'al hydroxide before use in the reaction. "In efieeting the condensation between "the resulting salty and primary nitroalcohol," water maybeemployed as the solvent. "I'he'condensatioripreduet-thus' obtained may be isolated and of a crystalline precipitate or oily liquid. Theproduct thus produced may be separated from the mother liquor by filtration or distillation and in this form is ordinarily in a state of suificient purity to meet the requirements of the majority of technical uses. If, however, it becomes necessary to purify the compound further, this object may be accomplished bydissolving the product, if a solid, in a suitablesolvent such as methanol, ethanol, butanol, or acetone, and boiling the resulting solution in the presence of decolorizing carbon, after which the mixture is filtered and the purified product obtained by recrystallization from the filtrate or by further distillation if it is a liquid.

The primary nitroparafiins operative in my process may be represented by the following formula:

R- -H 1'1 wherein R is alkyl. Examples of nitroparaflins included by the above formula are nitroethane, 1-nitropropane, 1-nitrobutane, l-nitropentane, l-nitrohexane, and the like.

Among the phenyl amines which can be used in my process there may be mentioned aniline, m-, and p-chloroaniline, dichloroaniline, o-, m-, and p-toluidine, o-, m-, and p-nitroaniline, 2,4 dimethylaniline, 2,4 dichloroaniline, 2- methyl-4-diethylaminoaniline, 4- N,N dimethylaminoaniline, 4-aminobiphenyl (4 phenylaniline) the following amines and their alkali metal salts: o-, m-, and p-hydroxyanilines, o-, m-, and p-sulfoanilines, om-, and p-carboxyanilines, 2,3-dicarboxyaniline, 4-methyl-3-sulfoaniline, 2-methyl-4-hydroxyaniline and the like.

Suitable nitrohydroxy compounds which may be utilized are represented by the formula:

wherein R is an alkyl radical. Examples of suitable nitrohydroxy compounds are 2-nitro-2- methyl-1,3-propanediol; 2-nitro-2-ethyl-1,3epropanediol; 2-nitro-2-propyl 1,3 propanediol; 2- nitro-2-butyl-1,3-propanediol; 2-nitro-2-pentyl- 1,3-propanediol; 2-nitro-2 hexyl-l,3 1oropanediol, and the like.

The presence of. a basic material either employed as catalyst or provided by the nature of reactants is necessary to the reaction, in the absence of such a basic. condition, no reaction appears to take place. The quantity of catalyst if employed may vary; however, in most instances it will be found desirable to employ the catalyst in concentrations of a least about 0.02%, based upon the weight of the aromatic amine used. In general, it may be said that the quantity utilized in excess of 0.02% is not critical. The basic catalyst may be an inorganic base such as sodium or potassium hydroxide, or it may be organic such as a tertiary organic amine, a quaternary ammonium compound, or the like. Certain catalysts such as pyridine, triethylamine, or tributylamine may serve a two-fold purpose in certain instances, since these particular compounds v ides of the alkali metals, such as sodium and potassium hydroxides, also serve as suitable catalysts for the reaction.

The following examples describe certain of the new nitroamines, and methods for their preparation; however, they are not to be in any Way construed as limiting my invention, since I have found that the reaction between aromatic amines of the type mentioned above, with formaldehyde and the primary nitroparaiiins described, or the corresponding dihydroxy nitro compounds prepared therefrom is very general and may readily be effected when carried out in the presence of a suitable basic catalyst.

EXAMPLE I A mixture consisting of 196 parts of aniline, parts of 2-nitro-2-methyl-1,3-propanediol and 5 parts of trimethylbenzylammonium hydroxide was permitted to react at a temperature of 50 C. with occasional agitation. As the reaction progressed, a layer of water was observed to form on top of the reaction mixture, and when further formation of water had apparently ceased, the crude mass was allowed to stand at room temperature, whereupon a yellow crystalline product precipitated. After one recrystallization from methanol, a total of 201.2 parts of yellow crystalline 2-nitro 2 methyl N,N' diphenyl-1,3-propanediamine, melting at 110.2 C. was obtained, corresponding to a yield of 70.5%.

Nitrogen analysis: Calculated-14.7%; found 14.52%.

, EXAMPLE II Z-mtro-Z-ethyl-MN-diphenyZ-1,3-propanediamine One-hundred and forty-nine parts (1 mole) of -2-nitro-2-ethyl-1,3-propanediol were mixed with 186 parts (2 moles) of aniline in a reaction vessel. Three and three-tenths parts of potassium hydroxide dissolved in 17 parts by volume of methanol were added and the mixture was warmed until the glycol dissolved. The mixture was then placed in a constant temperature water bath at 50 C. for 42 hours. To the resulting oily product was added 200 parts by volume of benzene whereupon two liquid layers formed. The water layer was removed and the benzene was evaporated to recover the 295 partsliquid 2-nitro -2- ethyl -N,N'- diphenyl -1,3- propanediamine, corresponding to a yield of 98%. This compound had a brown color. Its nitrogen content Was found to be 13.27%. Theoretical 14.03 Refractive index N 1.585; Y

sp. gr. C. 1.134

- EXAMPLE Z-m'tro -Z-mcthyl-N,N'bis (p-chlorophenylI-LS- propanediamz'ne '"methylalcohol were added thereto.

placed in-a water bathat 50 C. ior 42 hours.

yield of-yellow-eolored 2-nitro-2'methyl-N,N'-dip tolyl 1,3+propanediamine was 259.5 parts or 133%. Ithada melting point of 14628 0. Its

umerrofmethanol. .The mixture washeatedauntll ithe'gglycol rdissolved rand was ithen cplacedrin :a "water bath at 5051C. 'forz4i2ihours." The mixture amountedzto 68.6 :parts, correspondingato a :yield -of 441% .of 2+nitro-2-methyl-FNgNebisep-chloro- *phenyl-1;3-.propanediamine. T h e .;show.ed :anitrogen contentof. 11333 as compared to theoretical of 11.82 for atl'iisicompcund and a ;melting:point of 140 C.

ExA rIiETIVf I ..z-mtro-zmethyl-MN am-toned,am anediamine g V '-'I--wo-hundred' and fourteen parts '(2 moles of p-toluidine were mixed with 135 parts (1 mole) of 2-nitro-2-methyl-1,3 propanedioland--3".5 parts offpotassiumhydroxide in 13 parts by volume of The mixture waswarmeduntiltha glycol dissolved andthen The nitrogen content analyzed 12.96 as compared to '13'.4"theoretical value for this compound.

7 7 EXAMPLE V 'ZmitTO Z-m'ethyZ-NW'Jais(p-nitrophenyll-lj =propane'dz'amine Two-hundred and seven parts (1.5 moles) of ,p-nitro aniline were mixed with 10l.5lparts (.75

mole) of1'2-nitro2-methyl 1;3 propan'ediol .and' '3 parts of. potassium hydroxide dissolved in' 115 parts "by volume of methyl alcohol were'a'dded.

'Thevmixture wasplacedin awater b'athjat 50 "C.

for .42 hours, whereupon a yellow pasty mass formed. This mass was refluxed with 500 parts by volume of methyl alcohol and allowed to stand overnight, whereupon the mass was centrifuged and-the resulting yellow solid removed and dried,

resulting in 159.8 parts of 2-nitro-2-rnethyl-N',N-

2-nitro 2-?21,ethyZN,N-'- bis (p-nydmeyphenyz) 1,3-p1'opanediamine Ninety parts (0.817 mole) of p-aminophenol were mixed with 55 parts (0.48 mole) of 2-nitro- 2-methyl-1,3-propanediol and 1.4 parts of potassium hydroxide dissolved in 107.5 parts by volume of methyl alcohol were added. Then the mixture was placed in a water bath at 50 C. for 42 hours. The resulting colorless solid, 2-nitro-2- methyl-N,N'-bis(p-hydroxyphenyl) -1,3-propanediamine was recrystallized from butyl alcohol and 25.? parts of the colorless crystals were recovered, amounting to a yield of This compound had a melting point of 170 (dec0mp.) and a nitrogen content of 12.94% as compared to a theoretical of 13.22%.

EXAMPLE VII Z-nitro-Z-methyl-MN' -bis (o-carboxyphenyl) 1,3-1mopanediamine To 110 parts (0.805 mole) of anthranilic acid were added 254 parts by volume of 3.38 normal potassium hydroxideinmethyl alcohol, then 55 parts (.40 mole) of2 riitro{2-methyl-1,3-propanediol. This mixturewas -al-lowed-.to-stand at room temperature for 15 days 'and was then treated .5 with dilute HCl'to convertthe'sodium salt to the desiredacid. The black gummy solid which precipitated was dissolved in butanol and reprecipitated with .cyclohexane. Upon filtering and Washing with naphtha, 116 ,parts of bluish-black solid 2-nitro-2-methyl-N,N-bis(o-carboxyphenyl)--1,3-propanediaminewas recovered, having a melting,,point of -16f7.5 and amounting to i a yield-of 39%. -Thenitrogencontentiound was -10.!7-8% -as compared to-atheoretical of 11.25 for 5 this compound.

' EXAMP E" VIII 'Amixture of "186 parts .of .aniline,"7.5 .parts of nitroethane, 500parts of methanolgand11.9Zpaits of potassium hydroxide was heated to reflux and 150 .parts of 40% formaldehyde solution was "added over ,aperiod'of 'four hours. Reflux was continued for 'four. hours .more after the .formaldehyde was'added. When the solution cooled, two layers formed. The entire mixturewas vacuum'distilled until free frommethanol and water. Repeated cooling of theiresidue in Idry iceprodu'ced crystals which, when separatedand dried, amounted to '31 .parts. "Recrystallization from methanol resulted inhr'ightyellow crystals melt- .ing at 111 C. and containing 141.4% nitrogen '(theory"14.'7% Hydrogenation .of the mother liquor to ;2-jamino 2-m'ethyl=N,N-diphenyle-1,3- propanediarnine indicatedl that the .actual yield was about of theory.

:Prepamtion m EXAMPJZEII'X M Preparation of 2-nitro-3-methyl-N,N'abis(pnitrophenyl) -'1.,3.-propanediamine A mixture of 62.6,parts of p-nitroaniline, 17' Ar 'partsof *nitroethane, 225 "parts of methanol .and'.

-'while'-34 parts of-formaldehyde was added in one. "hour. Reflux was "continued for four hours. When the mixture was "cooled, yell'ow crystals: came out. These amounted'to "42.3 parts and proyedto be p-nitroaniline. The mother "liquor was evaporated to a' smaller Volume and cooled to inducecrystallization. The dry crystals amounted to23 parts "corresponding Tto a conversion of "27% and-yield of 83%based on p=nitroaniline. Recrystallization from butanol gave bright yellow, bulky, fibrous crystals which melted at 240 C. and contained 17.9% of nitrogen (theory 18.6% nitrogen).

EXAMPLE X Preparation of Z-mtro-Z-methyl-MN'-di-p-tolyl- 1,3-propanediamz'ne A mixture of 97 parts of p-toluidine, 34 parts of. nitroethane, 200 parts of methanol and 1.33 parts of potassium hydroxide was heated to reflux and. 68 parts of formaldehyde solution was dropped in in 2 /2 hours. Reflux was continued for three hours. When cooled, a large quantity of crystals formed which, when separated and dried, amounted to 118 parts corresponding to a yield of 76.6%. Recrystallization from methanol gave cream colored crystals which melted at 147 C. and contained 12.9% of nitrogen. nitrogen 13.4%.)

(Theoretical.

EXAMPLE XI Preparation of Z-m'tro-Z-methyZ-N,N'-bis(pchlorophenyl) -1,3-propanediamine A mixture of 127.5 parts of p-chloroaniline, 37.5 parts of nitroethane, parts of trimethylbenzylammonium hydroxide, and 300 parts of methanol was agitated and 75 parts of formaldehyde was added in three hours at slightly above room temperature. The mixture was then heated at 6065 for five hours and distilled till free from methanol. The oil layer of the residue was separated from the water and an equal volume of butanol was added and the solution was cooled in dry ice and allowed to warm to room temperature. This caused the formation of crystals which, when separated and dried, amounted to 59.2 parts corresponding to a yield of 33.4%. Recrystallization from methanol gave yellow crystals which melted at 137 C. and contained 11.52% nitrogen (theoretical nitrogen 11.85

The nitroamines of the type described above are useful in the preparation of compositions having a wide variety of valuable characteristics, such as for example, dyes, anti-skinning agents, indicators, pharmaceuticals, photographic preparations, and the like.

It will be noted that in the above specific examples the phenyl groups of the nitroamines produced by the described processes are substituted with a substituent selected from the group consisting of halogen, alkyl, N02, OH and COzH.

While the above describes the preferred embodiments of my invention, it will be understood that departures may be made therefrom within the scope of the specification and claims.

What is claimed is:

1. 2-nitro-2-methyl-N,N-bis(o carboxyphenyl) -1,3-propanediamine.

2. 2-nitro-2-ethyl-N,N'-diphenyl-1,3-propanediamine.

3. 2-nitro-2-methyl-N,N'-di-p-t0lyl 1,3 propane-diamine.

4. A process for preparing 2-nitro-2-methyl- N,N-bis(o-carboxyphenyl) -1,3 propanediamine which comprises reacting an alkali metal salt of anthranilic acid with formaldehyde and nitroethane, in the presence of a basic catalyst and in the proportions of about 1 mole of the nitroethane to 2 moles of formaldehyde and 2 moles of the anthranilic acid, and thereafter treating with an acid.

5. A process for preparing 2-nitro-2-ethyl- N,N'-di-p-tolyl-1,3-propanediamine which comprises reacting aniline with formaldehyde and nitroethane, in the presence of a basic catalyst and in the proportions of about 1 mole of the nitroethane to 2 moles of formaldehyde and 2 moles of the aniline.

6. A process for preparing 2-nitro-2-methyl- N,N'-di-p-tolyl-1,3-propanediamine which comprises reacting p-toluidine with formaldehyde and nitroethane, in the presence of a basic catalyst and in the proportions of about 1 mole of the nitroethane to 2 moles of formaldehyde and 2 moles of the p-toluidine.

7. The process of claim 8 in which the basic catalyst is an alkali metal hydroxide.

8. In the production of diamines the process which comprises causing a reaction in the presence of a basic catalyst between formaldehyde, a l-nitroalkane containing more than one carbon atom and a primary phenyl amine selected from a class consisting of phenyl amine and phenyl amines which are substituted in the nucleus with substituents which are non-reactive during'the following condensation reaction, by heating a mixture thereof, in the proportions of about 1 mole of the nitroalkane to 2 moles of formaldehyde and 2 moles of the phenyl amine, to a temperature ranging from at least about 25 C. to the reflux temperature of the mixture to promote a condensation reaction and then recovering the resulting diamine.

9. The process of claim 8 wherein the formaldehyde and the l-nitroalkane in the reaction mixture are derived from the decomposition in situ of a 2-nitro-2-alky1-1,3-propanediol.

10. As novel compounds, symmetrical 2-nitro- 2-alkyl-N,N'-diphenyl 1,3 propane diamines in which the phenyl groups are selected from a class consisting of phenyl and phenyl groups substituted with a substituent selected from the group consisting of halogen, alkyl, N02, OH and CO2H.

HAROLD G. JOHNSQN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,292,212 Dickey Aug. 4, 1942 2,298,375 Hasche Oct. 13, 1942 OTHER REFERENCES DeManny, Bul. Soc. Chim. de France, (5) 4, (1937), pages 1454 to 1458.

Certificate of Correction Patent No. 2,447,653. August 24, 1948.

HAROLD G. JOHNSON It is hereby certified that errors appear in the printed specification of the above numbered patentrequiring correction as follows: Column 6, line 41, Example IXQ'" for2-nitro-3-methyl read 2-m'tro-2- methyl; column 7, line 54, claim 5, for di-p-tolyl read diphenyl; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 16th day of November, A. D. 1948.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

